When is Radiosurgery Performed More than Once? Chapter 12 - Brain Metastases: A Documentary скачать в хорошем качестве

When is Radiosurgery Performed More than Once? Chapter 12 - Brain Metastases: A Documentary

This chapter explains why some radiosurgery treatments need more than one session to complete. Watch the entire documentary from the beginning here:    • Brain Metastases: A Documentary | How Brai...   The nature of how larger tumors reacts to radiation sometimes makes it necessary to treat them over a few sessions. ---------------------------------------------------------------------------------------------------------- Video Transcript: Dwight Heron, MD: Increasingly, we’re faced with more complicated, complex tumors, larger tumors, and tumors that are in close proximity, they are very close to critical structures, for instance, say the optic chiasm or the brain stem or one of the major cranial nerves. Giving a single fraction would be problematic, it would cause too much of a side effect. And so, the technologies that we have today with our relocatable frame, with our image guidance and our ability to vary the intensity of the radiation beam, has allowed us to give an effective dose of radiation by breaking it up into smaller fractions, something called “hypofractionation”. For instance, for the smallest tumors, we may give 21 or 24 Gy, and that’s a measure of radiation, in a single fraction. But for a tumor that’s say three centimeter, we may give you a much lower dose, which is 16 Gy and that doesn’t make any sense because a bigger tumor will have more cells that need to be killed. So why are we giving a lower dose? It’s because if we try to give 24 Gy to that three centimeter tumor, the side effect, meaning swelling and necrosis, which is dying brain tissue, would be unacceptably high. David Roberge, MD: In between the treatments, the normal brain can repair. In between the treatments, some areas of the tumor that were more resistant to radiation, maybe because they weren’t getting enough oxygen, can get more oxygen and become more sensitive to radiation. DH: All cells in the body require oxygen and tumors themselves have a higher demand on oxygen consumption just because they’re growing so rapidly. They can actually outgrow their blood supply. And when they outgrow their blood supply, they become what’s called ‘hypoxic’. So there is little oxygen towards the centers of the tumor. Incidentally, by giving a smaller dose of radiation but giving it in multiple fractions we’d get the benefit of having the tumor shrink and then that portion that was hypoxic actually has now more blood supply and as it further shrinks it gets even more blood supply, so the radiation is now more effective because there’s more oxygen around, there’s more free radical to damage the cancer cells and you get a better response to treatment. DR: For some large tumors, the future might be to be giving three and five treatments as opposed to just one treatment and again, if you have a system that doesn’t rely on screwing something to the patient’s head, then you have that flexibility of what’s best for this tumor. If it’s three treatments, we’ll do three treatments. If it’s one, we’ll give one and the quality and the accuracy will be the same. ---------------------------------------------------------------------------------------------------------- Interested in learning more? See our other chapters below that address many questions regarding brain metastases: What are brain metastases?    • What are Brain Metastases? Chapter 1 — Bra...   How do brain metastases develop and what causes them?    • What Causes Brain Metastases? Chapter 2 — ...   What are the possible treatment options for brain metastases?    • Is Chemotherapy Effective for Brain Metast...   What is Whole Brain Radiation Therapy (WBRT) and how is it used to treat brain metastases?    • What is Whole Brain Radiation Therapy (WBR...   What is stereotactic radiosurgery?    • What is Stereotactic Radiosurgery? Chapter...   What is the Gamma Knife?    • What is the Gamma Knife? Chapter 6 — Brain...   What is a linear accelerator and how does it work?    • What is a Linear Accelerator? Chapter 7 — ...   Frame-based vs. frameless radiosurgery. 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How do brain metastases patients maintain their quality of life?    • What Happens After Radiosurgery? Chapter 1...   Why is surgery sometimes necessary to treat brain metastases?    • When is Surgery Recommended? Chapter 15 — ...   Do you ever need to have both surgery and radiosurgery to treat brain metastases? Why?    • Do You Ever Need Both Surgery and Radiosur...   How do I choose the best care team for treating my brain metastases?    • How to Choose the Best Radiosurgery Treatm...   What is the future outlook a brain metastases diagnosis?    • What is the Future of Brain Metastases Tre...